| 摘要 |
PROBLEM TO BE SOLVED: To enhance the strength and toughness of crystals themselves, to considerably improve resistance to cracking and plastic deformation at high temp. and to ensure high strength and high toughness over the range from room temp. to high temp. by dispersing metal oxide crystal grains different from alumina and mullite crystal phases in the grains of the alumina and mullite crystal phases of a combined sintered compact contg. the crystal phases as the principal crystal phases. SOLUTION: This sintered compact contains metal oxide crystal grains contg. one or more among Ti, Mg and Fe and preferably having <=500μm grain diameter preferably by 0.5-10wt.% (expressed in terms of oxide) of the total amt. The amt. of mullite in this sintered compact is not especially limited but is preferably 5-80wt.% of the total amt. A powdery mixture of alumina and mullite or silicon oxide with the above-mentioned metal oxide having different solubility limits in alumina and mullite in correspondence with different atmospheres is compacted in an arbitrary shape, the resultant compact is sintered in an atmosphere in which the solubility limit is increased and the sintered compact is heat-treated in an atmosphere in which the solubility limit is reduced. |
